The present invention relates to a sliver severing device installed at the output of a draw frame to sever a delivered fiber sliver. Fiber sliver severing becomes necessary when the can has reached a state of fullness and must be replaced by an empty can.
According to the state of the art, safe severing of the fiber sliver in preparation of can replacement comprises severing the fiber sliver below the rotary plate, i.e. severing of the fiber sliver between the outlet of the rotary plate and the depositing in the can. This severing has, however, the disadvantage that following the severing operation, the remaining sliver end hangs from the outlet of the rotary plate. This involves the risk that the hanging sliver end may not completely enter an empty can which is subsequently provided. This may lead to interference with sliver deposit.
The solution according to DE-OS 38 07 239 places the severing device in the area between sliver funnel and calender rollers. This solution is based on the fact that, in the past, the severing of the fiber sliver was effected merely by briefly increasing the distance between sliver funnel and the pair of calender rollers. The sliver funnel was used as the moving element. It was disadvantageous that no second clamping of the fiber sliver was provided. This disadvantage is eliminated by DE-OS 38 07 239 in that the fiber sliver is clampingly held on the side of the sliver funnel and in that the severing operation occurs only then as a result of the change in distance due to the movement of the sliver funnel changing its location. Once the fiber sliver has been torn off, the distance between the sliver funnel and the pair of calender rollers is again reduced to the original distance.
The described solution has the disadvantage that this clamping device must also be included in the location-changing movement of the sliver funnel.
The prior solution has, however, also the disadvantage that the tearing point in the sliver above the pair of calender rollers is variable, and that the sliver end is released after the stopping of the calender rollers through the subsequent rotation of opening (additional effort) of the fiber guiding channel.